1. Field of the Invention
The present invention relates to agricultural planters, and, more particularly, to agricultural planters having individual row units that can be raised and lowered.
2. Description of the Related Art
Agricultural planters are commonly used implements to plant seeds in soil. An agricultural planter can include a chassis that carries one or more storage tanks full of seeds or other particulate that is to be spread on a field for planting, a hitch mechanism that attaches to a tractor or other implement pulled by a tractor, and a tool bar to which row units can be connected so that they are carried by the chassis.
Each row unit of the agricultural planter places seeds in the field. Typically, the row units are laterally arranged along a length of the tool bar so that as the planter is pulled across the field, each row unit plants seeds at predefined intervals along the path it is pulled across. To plant seeds, the row units perform four main operations as they are pulled: opening a trench in the soil; placing a seed into the formed trench at appropriate intervals; closing the formed trench to put soil on top of the placed seed; and packing soil on top of the seed to provide desirable soil contact with the placed seed. To open a trench in the soil, a furrowing disc, also called an opening disc, presses into the soil and rotates, dislocating soil as it rotates to form the trench. Once the trench is open, a seed is placed in the trench by a metering device which receives seeds from the main storage tank(s) or a row unit storage tank and typically utilizes a combination of differential air pressure and gravity to place the seed in the trench at predefined intervals along the pulled path so that adjacent seeds in the row are not too close to one another. One or more closing discs carried behind the furrowing disc are pressed into the soil and also rotate as the planter is pulled to replace soil dislocated by the furrowing disc in the trench or dislocate adjacent soil into the trench to cover the seed placed in the trench with soil. Finally, one or more pressing wheels carried behind the closing disc(s) exerts pressure on the soil covering the seed to press the soil down onto the seed and provide good soil contact with the seed. By having multiple row units working in unison as the planter is pulled across a field, many seeds can be effectively planted in an efficient manner.
Agricultural planters, like other agricultural implements, are often very wide, in order to efficiently perform their function over a large area in a given pass by the implement. In order to accomplish this, and yet to be transportable by road, they are often built to be folded into a transport configuration and unfolded into a working configuration. Additionally, given this very wide working configuration, agricultural planters and other agricultural implements are commonly provided with articulating hinges or joints that allow them to conform to ground contours. Such wide agricultural planters often encounter conditions wherein it is suitable to operate certain row units, while deactivating other row units. It is known to raise and lower sections of row units in unison. However, it is sometimes needed to be able to raise and lower individual row units in order to respond to specific usage requirements, such as when the plantable ground is smaller than the usable width of the agricultural planter, or when natural ground conditions or obstacles call for it.
Under these conditions, a sudden and/or uneven raising of row units can introduce unwanted uneven weight or drag distribution, with detrimental effects on the agricultural planter or on the tractor pulling it. Further, raising too many row units in one portion of the agricultural planter may cause it to sink excessively and compact the soil unnecessarily. Additionally, responding to a command to raise or lower an individual row unit without considering the state of the agricultural planter may result in the individual row unit being raised or lowered when the tool bar height prevents full travel of the row unit.
What is needed in the art is an agricultural planter that is operable to automatically or manually respond to specific usage requirements of the row units, such as the plantable ground being less than the overall width of the agricultural planter, and to natural ground conditions, such as rough terrain, ditches, streams, obstacles, and the like, while recognizing and avoiding raising and lowering individual row units under certain conditions such as ground conditions or conditions that would result in unsafe uneven weight or drag distribution.